1,1,1,2-tetrafluoroethane (HFC-134a), as an alternative to CFC-12, has been widely used with its excellent performance. However, due to its high value of GWP up to 1430, it has been listed in one of the refrigerants with high GWP that are firstly eliminated in “Kyoto Protocol”. For HFC-134a used in the small refrigeration equipments, most of them have been substituted by HC-600a, while for the alternative to HFC-134a used in the industrial and commercial refrigeration and air-conditioning in cars, it has become a hot issue to be resolved urgently across the world.
At present, internationally, the main alternatives to HFC-134a are carbon dioxide (CO2), 1,1-difluoroethane (HFC-152a), 2,3,3,3-tetrafluoropropene (HFO-1234yf), etc. But they have their advantages and disadvantages. CO2 is environmentally friendly and non-combustible, but the system pressure is high, the energy efficiency is low, and the system should be re-designed with high costs. HFC-152a has a high energy efficient and low price of refrigerant, but its flammability is strong and it is necessary to add secondary loop, which causes a high costs. HFO-1234yf has low flammability, small system transformation but its energy inefficient is low and the cooling capacity is low. Therefore, the studies on the alternative to HFC-134a have been continuously carried out in various countries across the world, and mixed refrigerant is a major research field.
In the prior art, Patent Document CN1285699C (200410084844.5) discloses a ternary composition composed of fluoroethane (HFC-161), 1,1-difluoroethane (HFC-152a) and 1,1,1,2-tetrafluoroethane; CN101671542A (200910018489.4) discloses a mixture composed of 2,3,3,3-tetrafluoropropene (HFO-1234yf), 1,1-difluoroethane (HFC-152a) and isobutene; CN101864277A (201010196224. 6) discloses a mixture composed of 2,3,3,3-tetrafluoropropene (HFC-1234yf), 1,1-difluoroethane (HFC-152a) and dimethyl ether (DME); CN102703033A (201210165277.0) discloses a mixture composed of 2,3,3,3-tetrafluoropropene (HFC-1234yf), 1,1,1,2-tetrafluoroethane (HFC-134a) and dimethyl ether (DME); CN102066518A (200980122002.5) discloses a mixture composed of 2,3,3,3-tetrafluoropropene (HFC-1234yf), 1,1,1,2-tetrafluoroethane (HFC-134a) and 1,1-difluoroethane (HFC-152a); CN102083935A (200980125796.0) discloses a mixture composed of 1,1,1,2-tetrafluoroethane (HFC-134a) and 2,3,3,3-tetrafluoropropene (HFC-1234yf). CN102083935A (200980125796.0) discloses a mixture composed of 1,1,1,2-tetrafluoroethane firing (HFC-134a) and 2,3,3,3-tetrafluoropropene (HFC-1234yf); and CN102712837A (201080038152.0) discloses a mixture composed of 1,1,1,2-tetrafluoroethane (HFC-134a), 2,3,3,3-tetrafluoropropene (HFC-1234yf) and difluoromethane (HFC-32).
The refrigerant compositions disclosed in the above patents have such drawbacks as high GWP value, strong flammability, high temperature glide, low efficiency, small volume of cooling capacity, unable to be directly filled and used in HFC-134a system, etc. Therefore, it is necessary to develop an alternative refrigerant of HFC-134a with excellent cooling performance, better compatibility with existing systems, and better environmental performance.